A glitch in the online version of bookkeeping software Quicken has caused some accounts to duplicate transactions and may have resulted in incorrect information being displayed, Intuit confirmed Tuesday.

The glitch resulted when Intuit, which makes Quicken and other financial software, updated the software to conform to a new computer language, OFX, which is the new standard for exchanging financial data over the Internet. Mountain View, Calif.-based Intuit changed the language for online versions used at 15 different financial institutions, spokesman Chris Repetto said.

"This is an unfortunate side effect," he said.

Repetto said that only a small percentage of customers would be affected by the glitch. Out of the more than 40,000 Quicken bill-payment customers, Repetto said Intuit has received about 70 phone calls related to this issue.

The problem affects those who manually keyed in bill-paying transactions rather than having them automatically downloaded, as well as those who recently disabled their account. The only way for customers to fix the problem is by catching and deleting the erroneous information.

A customer of Pittsburgh-based PNC Bank said he spent more than five hours checking his records to catch the more than 150 duplicate transactions dating back from October that began pouring in over the weekend. When he downloaded the new version of Quicken from PNC's Web site, he was sent a link to Intuit's site that warned of the possibility of duplicate transactions during the switch.

"The first time you connect after this change is made, your financial institution may restore payments that are already in your register, causing the register balance to be incorrect," the notice read. The site offered instructions to help customers correct the problems.

"I had to go in and check the names, addresses and account information of everybody I pay," said Ken Schoenberg, who lives in Florida. "Do you know the address of your phone company? I don't."

Quicken is personal financial management software. On the computer screen, it looks much like a checkbook register. Online customers can automatically see all their financial information and keep track of their savings, brokerage and retirement accounts.

A customer service representative at PNC said the bank received many complaints from customers about the glitch.

There is some discrepancy about who was at fault for not warning customers about potential malfunctions.

The glitch should not have come as a surprise to any of the 15 financial institutions that offer Quicken, said Michael Klieman, senior product manager for Intuit. In March, Quicken warned the companies that this kind of malfunction could occur, he said.

"We got notification of the upgrade but were told that there would be no impact to our customers," said Melanie Lodge, manager of PNC's online banking operations. "No, they did not tell us this could happen."